Glycan-protein interactions determine kinetics of -glycan remodeling.

A hallmark of -linked glycosylation in the secretory compartments of eukaryotic cells is the sequential remodeling of an initially uniform oligosaccharide to a site-specific, heterogeneous ensemble of glycostructures on mature proteins. To understand site-specific processing, we used protein disulfide isomerase (PDI), a model protein with five glycosylation sites, for molecular dynamics (MD) simulations and compared the result to a biochemical analysis with four different glycan processing enzymes. As predicted by an analysis of the accessibility of the -glycans for their processing enzymes derived from the MD simulations, -glycans at different glycosylation sites showed different kinetic properties for the processing enzymes.